The present invention relates to a crimping appliance or tool for fastening ferrules, such as those associated with terminal connectors, and which are within a given size range, onto the ends of rod-like articles such as electrical conductors by way of a pair of cooperating dies forming a part of the tool.
The tool includes a pair of cooperating, elongated working jaws, and a pair of arm members on which the jaws are mounted, each jaw carrying one of the cooperating dies. The arm members are movable relative to each other between an open configuration or position at which the working jaws are separated from each other, and a closed configuration or position at which the working jaws close against each other or about an article placed between them.
Each arm member is situated at one end of a force transmitting path, the other end of which is at a point on the tool where an external force is to be applied (hereinafter "force application point"). For one of the arm members, the externally applied force operates as a driving force to provide closing movement to the arm member, the force application point being located on a driving mechanism associated with the arm member. For the other arm member, the externally applied force can also operate as a driving force to provide closing movement, or it can originate from a stationary clamp on a part joined to the arm member, the clamp serving to support the tool while the first mentioned arm member is operated.
A resilient member of predetermined hardness and strength is interposed in at least one of the force transmitting paths to compensate for the presence of an article between the working jaws by allowing the driving mechanism to be fully actuated by an externally applied force, even though the jaws cannot be fully closed. A pawl and ratchet locking mechanism prevents the driving mechanism from returning to its open configuration after relative closing movement of the arm member is initiated and before the driving mechanism is brought to its closed configuration.
An appliance or tool in the same category as the present invention is disclosed in British patent application Ser. No. 52366/77 or U.S. patent application Ser. No. 852,724 (now U.S. Pat. No. 4,199,972) of one of the co-inventors. In that tool, arm members and associated working jaws are pivotally movable relative to each other so that the tool operates in a tong-like manner. In the tool of the present invention, the arm members and the working jaws may also be arranged to move relative to each other over a straight or translatory path of movement to operate in a vise-like manner such as disclosed in, for example, British Pat. No. 1,141,179.
The term "working jaws", as used herein, refers to the particular parts which are adapted to perform the intended operation of the tool, i.e., the parts which are in the shape of, or provided with, the two cooperating crimping dies. The term "arm member", as used herein, refers to each part which is connected between a working jaw and a driving mechanism or handle. The term "force transmitting path", as used herein, refers to a path made up of parts of the tool which are rigidly or operationally interconnected and which extend between a working jaw at one end and a corresponding force application point at the other end, an externally applied force being transmitted through this path from the force application point to the working jaw.
It will be readily understood that it is usually desirable for a given tool to have the capability of performing work on articles whose sizes vary within as large a range as possible, thereby obviating the need for a number of different sized tools, or the need for interchangeable sets of working jaws. For example, crimping tools are known which have working jaws provided with three pairs of crimping dies of different dimensions, each pair consisting of a male and a female die. Such a crimping tool is shown, for example, in the British Pat. No. 1,141,179, wherein the female as well as the male die of each pair of crimping dies has a concave face for engaging a ferrule. Such a tool does not offer the possibility of satisfactorily treating ferrules having diameters lying between the discrete values which correspond to the die pairs provided.
A tool which can work on ferrules having diameters within a given size range is disclosed in British Pat. No. 1,523,160 or U.S. Pat. No. 4,078,303 of one of the co-inventors. The working jaws of the tool each have a number of projecting transverse webs positioned one behind the other in the axial direction of the article to be treated, so that gaps are provided between adjacent webs. The construction of the working jaws is quite elaborate and, therefore, expensive in that each projecting web has one rather narrow engagement face for grasping the article to be worked on, and about half of the engagement faces on each jaw lie in a first hypothetical plane which is inclined to a plane of symmetry of the respective jaw from a first side of the jaw, and the remainder of the engagement faces on each jaw are contained in a second hypothetical plane which is inclined to the plane of symmetry of the jaw from a second, opposite side of the jaw. During the course of closing movement of the jaws relative to each other, the projecting webs on one jaw penetrate gradually into the gaps between the projecting webs of the other jaw, the engagement faces of all the projecting webs defining a quadrilateral channel or opening which continuously decreases as the jaws approach one another. Both jaws are similar in form so that neither of them can be described as a male or a female die. Production of these jaws is however quite expensive in view of the number of projecting webs with the gaps between them and the engagement faces each of which lie in one of four different planes.
An object of the present invention is to provide a crimping tool having working jaws which can be produced at relatively little expense.
In accordance with the present invention, a crimping tool includes a pair of working jaws with a male die on one of the working jaws and a female die on the other. The female die is defined by an elongated notch, the sides of which taper toward each other from the longitudinal opening of the notch to a closed end wall of the notch, the notch having a depth in its transverse cross-section which is substantially equal to the transverse width of its longitudinal end opening.
The tool also includes an elongated male die on the other working jaw, the height of the male die in transverse cross-section being substantially equal to the depth of the female die. The male die is shaped and dimensioned so as to be fully contained within the notch of the female die when the working jaws are closed against each other.
A driving mechanism is provided for moving the arm members relative to each other between an open configuration and a closed configuration, and a locking mechanism associated with the driving mechanism operates to prevent the arm members from moving toward their open configuration unitl the driving mechanism is fully actuated to a closed configuration corresponding to closure of the working jaws without an article placed between them. A resilient member associated with at least one of the jaws operates to compensate for less than full closure of the jaws when an article is placed between them so that the driving mechanism can be fully actuated thereby allowing the arm members to return to their open configuration.
The tool of the present invention can thus accommodate ferrules having any diameter up to the depth of the notch in the female die. The ferrules will be pressed into the notch of the female die by the male die in response to a compressive force which increases with the diameter of the ferrule. It will be understood that the compressive force increases according to the size of the ferrule because further compression of the resilient member is required when a larger article is inserted between the working jaws than when a smaller article is so placed. Since the fully actuated configuration of the driving mechanism, at which it is released by the locking mechanism, is always the same, additional force must be applied to the tool and, hence, to a larger ferrule to further compress the resilient member while bringing the driving mechanism to its fully actuated or closed configuration. The final distance between the closed end wall of the notch in the female die and the leading face of the male die will be the greater, the greater will be the final dimension of a ferrule crimped by the dies in the direction of the closing movement of the working jaws. As used herein, the terms "empty working jaws" or "working jaws in an unloaded state" refer to the condition when no work pieces, e.g. a ferrule, is inserted between the working jaws.
It has been found that ferrules of widely varying diameters can be best accommodated when the notch in the female die in transverse cross-section is in the shape of a parabola, or at least a piecewise or sectional linear approximation of a parabola, rather than simply being in the form of a "V". A piecewise linear approximation is realized when each side of the notch in transverse cross-section is formed by at least two straight line sections which form an obtuse angle and are substantially tangent to a given parabola. The number of straight sections chosen depends on how close an approximation to the parabola is desired and which can be practically achieved. A straight line section extending between the sides of the notch in transverse cross-section is tangent to the apex of the parabola. This line section corresponds to the elongated closed end wall of the notch which extends longitudinally in a plane between the notch side walls.
The male die can either be entirely complementarily shaped with respect to the notch in the female die, or it can have any other shape which does not extend beyond the bounds of such a complementary shape, as will be explained in further detail below.
In vise-like tools, a pair of jaws approach each other while the jaw faces remain in parallel relationship to each other. However, in tong-like tools having arm members which move pivotally relative to each other, the arm members approach each other in an inclined relationship. Therefore, with tong-like tools, jaws having elongated working portions must be mounted either with the elongated portions at right angles to the plane of pivotal movement of the arm members, or in the plane of the pivotal movement with at least one of the working jaws being pivotally mounted to a corresponding arm member for rotation about an axis perpendicular to the plane of the pivotal movement. By such mounting, parallel alignment of the two working jaws can be realized when the jaws contact each other or an article inserted between them.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention .